Constraining r-process nucleosynthesis via enhanced accuracy neutron-capture experiments

Abstract The isotopic abundances of r-process elements in the solar system are traditionally derived as residuals from the subtraction of s-process contributions from total solar abundances. However, the uncertainties in s-process nucleosynthesis – particularly those arising from Maxwellian Averaged Cross Sections (MACS) – propagate directly into the r-process residuals, affecting their reliability. Building upon the seminal work of Goriely (A&A 342:881–891, 1999), who introduced a multi-event s-process model to quantify these uncertainties, we revisit the problem using a simplified yet effective approach. By assuming that the relative uncertainty in s-process isotopic abundances scales linearly with the MACS uncertainties from data libraries (KADoNiS), we identify a subset of isotopes for which the r-process residuals remain significantly uncertain. Using updated solar abundances (Lodders in Space Sci Rev 221:23, 2025) and s-process contributions from Bisterzo et al. (ApJ 787:10, 2014), we present a short list of isotopes that are prime candidates for improved ( $$n,\gamma $$ n , γ ) measurements at CERN n_TOF in the near future. Our analysis provides a practical framework for prioritizing future experimental efforts that will profit from upgrades and enhancements of the n_TOF facility. It also highlights the need to revisit key neutron-capture cross sections to refine our understanding of the r-process isotopic abundance pattern, commonly used as a benchmark in stellar models of explosive nucleosynthesis.